Switch from conventional to high-flux membrane reduces the risk of carpal tunnel syndrome and mortality of hemodialysis patients

Carpal tunnel release in the dialysis-dependent population: Incidence and outcomes

Level of evidence

Level III, retrospective case-control study.

Background

The association between dialysis and carpal tunnel syndrome is well-established. As the number of patients living with dialysis-dependent end-stage renal disease (ESRD) increases, it is important that we understand outcomes after carpal tunnel release in this population.

Purpose

To investigate (1) the prevalence of carpal tunnel syndrome (CTS) in dialysis-dependent patients, (2) the incidence of carpal tunnel release (CTR), and (3) the differences in complications after CTR between hemodialysis patients, peritoneal dialysis patients, and matched controls.

Patients and methods

Querying the PearlDiver database, we determined prevalence of CTS and incidence of CTR in dialysis-dependent and control patients. We compared peritoneal dialysis (PD) patients to matched populations of hemodialysis (HD) patients and non-dialysis-dependent controls. Complications were identified, including hospital admission, emergency department visits, infection, revision surgery, and postoperative chronic regional pain syndrome (CRPS).

Results

The rates of CTS and CTR in dialysis patients were significantly increased relative to controls. Dialysis-dependent patients had increased rates of hospital admission within 30 days postoperatively (OR 4.13, P ​< ​.0001 for PD; OR 4.42, P ​< ​.0001 for HD), infection within 6 months postoperatively (OR 2.32, P ​= ​.013 for PD; OR 3.20, P ​< ​.0001 for HD), and need for revision CTR (OR 2.04, P ​= ​.009 for PD; OR 1.62, P ​= ​.037 for HD). Emergency department presentation within 30 days postoperatively was less common in PD vs HD (OR 0.63, P ​= ​.038).

Conclusions

When compared to the control population, patients undergoing dialysis are more likely to be diagnosed with carpal tunnel syndrome, undergo carpal tunnel release, and are at significantly increased risk for perioperative complications.

Beta-2 Microglobulin Amyloidosis: Past, Present, and Future

Almost half a century has elapsed since the first description of dialysis-related amyloidosis (DRA), a disorder caused by excessive accumulation of β-2 microglobulin (B2M). Within that period, substantial advances in RRT occurred. These improvements have led to a decrease in the incidence of DRA. In many countries, DRA is considered a "disappearing act" or complication. Although the prevalence of patients living with RRT increases, not all will have access to kidney transplantation. Consequently, the number of patients requiring interventions for treatment of DRA is postulated to increase. This postulate has been borne out in Japan, where the number of patients with ESKD requiring surgery for carpal tunnel continues to increase. Clinicians treating patients with ESKD have treatment options to improve B2M clearance; however, there is a need to identify ways to translate improved B2M clearance into improved quality of life for patients undergoing long-term dialysis.

Convective-Controlled Double High Flux Hemodiafiltration: A Novel Blood Purification Modality

Convective-controlled double high flux hemodiafiltration (CC-DHF) was set-up using two high flux dialyzers. The convection occurred in the first while the fluid replacement took place in the second dialyzer. The system of CC-DHF basically resembled that of hemodiafiltration. CC-DHF was performed in 9 chronic hemodialysis Thai patients who had been treated with high flux hemodialysis for at least 6 months. When compared with high flux hemodialysis, CC-DHF could provide higher Kt/Vurea (2.4 ± 0.4 vs. 2.0 ± 0.4, p<0.05) and ß2-microglobulin clearance (106.2 ± 15.4 vs. 48.9 ± 6.1 ml/min, p<0.01). Following 6-month therapy of CC-HDF, the predialysis ß2-microglobulin levels were reduced by 12.7% while the values of Kt/Vurea were consistently higher than 2.7. The quality of life consistently improved during the 6 months of CC-DHF treatment. There were no differences in clinical and technical complications between CC-DHF and high flux hemodialysis. In conclusion, CC-DHF could provide performance comparable to hemodiafiltration without the need for expensive hemodiafiltration machines.

Effect of dialyzer membrane materials on survival in chronic hemodialysis patients: Results from the annual survey of the Japanese Nationwide Dialysis Registry

BACKGROUND

Little information is available regarding which type of dialyzer membrane results in good prognosis in patients on chronic hemodialysis. Therefore, we conducted a cohort study from a nationwide registry of hemodialysis patients in Japan to establish the association between different dialyzer membranes and mortality rates.

METHODS

We followed 142,412 patients on maintenance hemodialysis (female, 39.1%; mean age, 64.8 ± 12.3 years; median dialysis duration, 7 [4-12] years) for a year from 2008 to 2009. We included patients treated with seven types of high-flux dialyzer membranes at baseline, including cellulose triacetate (CTA), ethylene vinyl alcohol (EVAL), polyacrylonitrile (PAN), polyester polymer alloy (PEPA), polyethersulfone (PES), polymethylmethacrylate (PMMA), and polysulfone (PS). Cox regression was used to estimate the association between baseline dialyzers and all-cause mortality as hazard ratios (HRs) and 95% confidence intervals for 1-year mortality adjusting for potential confounders, and propensity score matching analysis was performed.

RESULTS

The distribution of patients treated with each membrane was as follows: PS (56.0%), CTA (17.3%), PES (12.0%), PEPA (7.5%), PMMA (4.9%), PAN (1.2%), and EVAL (1.1%). When data were adjusted using basic factors, with PS as a reference group, the mortality rate was significantly higher in all groups except for the PES group. When data were further adjusted for dialysis-related factors, HRs were significantly higher for the CTA, EVAL, and PEPA groups. When the data were further adjusted for nutrition-and inflammation-related factors, HRs were significantly lower for the PMMA and PES groups compared with the PS group. After propensity score matching, HRs were significantly lower for the PMMA group than for the PS group.

CONCLUSION

The results suggest that the use of different membrane types may affect mortality in hemodialysis patients. However, further long-term prospective studies are needed to clarify these findings, including whether the use of the PMMA membrane can improve prognosis.

Dialysis-related amyloidosis: challenges and solutions

Amyloidosis refers to the extracellular tissue deposition of fibrils composed of low-molecular-weight subunits of a variety of proteins. These deposits may result in a wide range of clinical manifestations depending upon their type, location, and the amount of deposition. Dialysis-related amyloidosis is a serious complication of long-term dialysis therapy and is characterized by the deposition of amyloid fibrils, principally composed of β2 microglobulins (β2M), in the osteoarticular structures and viscera. Most of the β2M is eliminated through glomerular filtration and subsequent reabsorption and catabolism by the proximal tubules. As a consequence, the serum levels of β2M are inversely related to the glomerular filtration rate; therefore, in end-stage renal disease patients, β2M levels increase up to 60-fold. Serum levels of β2M are also elevated in several pathological conditions such as chronic inflammation, liver disease, and above all, in renal dysfunction. Retention of amyloidogenic protein has been attributed to several factors including type of dialysis membrane, prolonged uremic state and/or decreased diuresis, advanced glycation end products, elevated levels of cytokines and dialysate. Dialysis treatment per se has been considered to be an inflammatory stimulus, inducing cytokine production (such as interleukin-1, tumor necrosis factor-α, interleukin-6) and complement activation. The released cytokines are thought to stimulate the synthesis and release of β2M by the macrophages and/or augment the expression of human leukocyte antigens (class I), increasing β2M expression. Residual renal function is probably the best determinant of β2M levels. Therefore, it has to be maintained as long as possible. In this article, we will focus our attention on the etiology of dialysis-related amyloidosis, its prevention, therapy, and future solutions.

Significance of the decreased risk of dialysis-related amyloidosis now proven by results from Japanese nationwide surveys in 1998 and 2010

BACKGROUND

Although dialysis technology greatly improved in recent years, it remained unclear whether those improvements helped decrease the incidence of dialysis-related amyloidosis (DRA). Accordingly, we retrospectively compared the incidence of first-time carpal tunnel surgery (CTS)-as proxy for DRA onset-in two cohorts of chronic hemodialysis patients, with the second cohort studied after dialysis methods (especially dialyzate quality control) had greatly improved.

METHODS

We used the 1998 and 2010 Japan Renal Data Registries to compare crude risk of first-time CTS the following year. After adjusting for patient background and laboratory data, odds ratios (ORs) for CTS in the whole cohorts and the populations matched by propensity score (PS) for hemodialysis and hemodiafiltration were calculated at a 95% confidence interval.

RESULTS

Of note, 2 02 726 patients were analyzed. In the 1998 cohort, 1.77% experienced first-time CTS compared with 1.30% of the 2010 cohort (P < 0.001); with 2010 as referent, the adjusted 1998 OR was 2.22 (1.68-2.95). Both crude risks and adjusted ORs were analyzed by dialysis vintage, age, pre-dialysis β2-microglobulin (β2m) and β2m clearance, risk of CTS trending 1.5-2.0 higher in 1998 than 2010. The reduction was most prominent in patients with longer dialysis vintage, patients who were younger, and those with lower pre-dialysis β2m levels. Similar results were obtained by PS-matched analysis. We also found that β2m clearance >80% may reduce risk of CTS.

CONCLUSIONS

The incidence of first-time CTS as proxy for DRA decreased significantly from 1998 to 2010. Several factors may have contributed to this decrease, including improved dialysis methods.

Dialyzer Reuse and Outcomes of High Flux Dialysis

Background

The bulk of randomized trial evidence for the expanding use of High Flux (HF) hemodialysis worldwide comes from two randomized controlled trials, one of which (HEMODIALYSIS, HEMO) allowed, while the other (Membrane Outcomes Permeability, MPO) excluded, the reuse of membranes. It is not known whether dialyzer reuse has a differential impact on outcomes with HF vs low flyx (LF) dialyzers.

Methods

Proportional Hazards Models and Joint Models for longitudinal measures and survival outcomes were used in HEMO to analyze the relationship between β2-microglobulin (β2M) concentration, flux, and reuse. Meta-analysis and regression techniques were used to synthesize the evidence for HF dialysis from HEMO and MPO.

Findings

In HEMO, minimally reused (< 6 times) HF dialyzers were associated with a hazard ratio (HR) of 0.67 (95% confidence interval, 95%CI: 0.48–0.92, p = 0.015), 0.64 (95%CI: 0.44 – 0.95, p = 0.03), 0.61 (95%CI: 0.41 – 0.90, p = 0.012), 0.53 (95%CI: 0.28 – 1.02, p = 0.057) relative to minimally reused LF ones for all cause, cardiovascular, cardiac and infectious mortality respectively. These relationships reversed for extensively reused membranes (p for interaction between reuse and flux < 0.001, p = 0.005) for death from all cause and cardiovascular causes, while similar trends were noted for cardiac and infectious mortality (p of interaction between reuse and flux of 0.10 and 0.08 respectively). Reduction of β2M explained only 1/3 of the effect of minimally reused HF dialyzers on all cause mortality, while non-β2M related factors explained the apparent attenuation of the benefit with more extensively reused dialyzers. Meta-regression of HEMO and MPO estimated an adjusted HR of 0.63 (95% CI: 0.51–0.78) for non-reused HF dialyzers compared with non-reused LF membranes.

Conclusions

This secondary analysis and synthesis of two large hemodialysis trials supports the widespread use of HF dialyzers in clinical hemodialysis over the last decade. A mechanistic understanding of the effects of HF dialysis and the reuse process on dialyzers may suggest novel biomarkers for uremic toxicity and may accelerate membrane technology innovations that will improve patient outcomes.

Uremic pruritus, dialysis adequacy, and metabolic profiles in hemodialysis patients: a prospective 5-year cohort study

Background

Uremic pruritus is a common and intractable symptom in patients on chronic hemodialysis, but factors associated with the severity of pruritus remain unclear. This study aimed to explore the associations of metabolic factors and dialysis adequacy with the aggravation of pruritus.

Methods

We conducted a 5-year prospective cohort study on patients with maintenance hemodialysis. A visual analogue scale (VAS) was used to assess the intensity of pruritus. Patient demographic and clinical characteristics, laboratory parameters, dialysis adequacy (assessed by Kt/V), and pruritus intensity were recorded at baseline and follow-up. Change score analysis of the difference score of VAS between baseline and follow-up was performed using multiple linear regression models. The optimal threshold of Kt/V, which is associated with the aggravation of uremic pruritus, was determined by generalized additive models and receiver operating characteristic analysis.

Results

A total of 111 patients completed the study. Linear regression analysis showed that lower Kt/V and use of low-flux dialyzer were significantly associated with the aggravation of pruritus after adjusting for the baseline pruritus intensity and a variety of confounding factors. The optimal threshold value of Kt/V for pruritus was 1.5 suggested by both generalized additive models and receiver operating characteristic analysis.

Conclusions

Hemodialysis with the target of Kt/V ≥1.5 and use of high-flux dialyzer may reduce the intensity of pruritus in patients on chronic hemodialysis. Further clinical trials are required to determine the optimal dialysis dose and regimen for uremic pruritus.

The impact of membrane permeability and dialysate purity on cardiovascular outcomes

The effects of high-flux dialysis and ultrapure dialysate on survival of hemodialysis patients are incompletely understood. We conducted a randomized controlled trial to investigate the effects of both membrane permeability and dialysate purity on cardiovascular outcomes. We randomly assigned 704 patients on three times per week hemodialysis to either high- or low-flux dialyzers and either ultrapure or standard dialysate using a two-by-two factorial design. The primary outcome was a composite of fatal and nonfatal cardiovascular events during a minimum 3 years follow-up. We did not detect statistically significant differences in the primary outcome between high- and low-flux (HR=0.73, 95% CI=0.49 to 1.08, P=0.12) and between ultrapure and standard dialysate (HR=0.90, 95% CI=0.61 to 1.32, P=0.60). Posthoc analyses suggested that cardiovascular event-free survival was significantly better in the high-flux group compared with the low-flux group for the subgroup with arteriovenous fistulas, which constituted 82% of the study population (adjusted HR=0.61, 95% CI=0.38 to 0.97, P=0.03). Furthermore, high-flux dialysis associated with a lower risk for cardiovascular events among diabetic subjects (adjusted HR=0.49, 95% CI=0.25 to 0.94, P=0.03), and ultrapure dialysate associated with a lower risk for cardiovascular events among subjects with more than 3 years of dialysis (adjusted HR=0.55, 95% CI=0.31 to 0.97, P=0.04). In conclusion, this trial did not detect a difference in cardiovascular event-free survival between flux and dialysate groups. Posthoc analyses suggest that high-flux hemodialysis may benefit patients with an arteriovenous fistula and patients with diabetes and that ultrapure dialysate may benefit patients with longer dialysis vintage.

Effects of high versus low flux membranes on o2 saturation in hemodialysis patients

Background

Several studies have been carried out to evaluate the effects of dialysis on O2 saturation. While the dialysis procedure may lead to hypoxia under different circumstances, there are few studies available on the effects of membrane type on O2 saturation in these patients.

objectives

This study was to appraise the effects of high and low flux membrane on pulse oxymetery in dialysis patients.

Patients and Methods

In a cross-sectional evaluation, 43 hemodialysis patients without pulmonary disease were enrolled. Of this group, dialysis was performed by low and high flux membranes, and pulse oxymetery was applied before and after the procedures.

Results

Mean age of the patients was 56.34 years. Of these patients, 23 (53.5%) and 20 (46.5%) were women and men, respectively. Type of membrane (high flux vs. low flux) did not show any significant effect on pulse oxymetery results (P > 0.05).

Conclusions

Due to the lack of a significant difference in pulse oxymetery and creation of hypoxia between two types of membranes in hemodialysis patients, as well as the high cost of high flux membrane as compared to the low flux membrane, we do not suggest the use of high flux membrane in dialysis.

Hemodialysis and hemodiafiltration differently modulate left ventricular diastolic function

Background

Renal replacement therapy may have a favorable effect on diastolic left ventricular function, but it is not clear whether hemodiafiltration is superior to hemodialysis in this field. Nitric oxide (NO) and asymmetric dimethylarginine (ADMA) may play a role in the changes of intracardiac hemodynamics, but it is not clear whether the different renal replacement methods have disparate influence on the metabolism of these materials.

Methods

Thirty patients on renal replacement therapy were investigated. First, data was analyzed while patients received hemodiafiltration over a period of three months. Then, the same patients were evaluated during treatment with hemodialysis for at least another three months. Echocardiography was performed before and after renal replacement therapy.

Results

No significant difference was found in the volume removals between hemodialysis and hemodiafiltration. The left atrial diameter and transmitral flow velocities (E/A) decreased significantly only during hemodiafiltration. A positive correlation was observed between the left atrial diameter and E/Ea representing the left ventricular pressure load during hemodiafiltration. Significant correlations between NO and A and E/A were observed only in the case of hemodiafiltration.

Conclusion

Hemodiafiltration has a beneficial effect on echocardiographic markers representing left ventricular diastolic function. This could be attributed to the differences between the dynamics of volume removal and its distribution among liquid compartments.

Effect of ultrapure dialysate on markers of inflammation, oxidative stress, nutrition and anemia parameters: a meta-analysis

BACKGROUND

Markers of inflammation are linked to malnutrition and confer an increased mortality risk in hemodialysis patients. Ultrapure dialysate might have a beneficial effect on markers of inflammation. We conducted a meta-analysis that examined the effect of ultrapure versus standard dialysate on markers of inflammation, oxidative stress, nutrition and anemia parameters.

METHODS

We performed a literature search using MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and scientific abstracts. Single-arm studies, nonrandomized and randomized controlled trials were included. We conducted random effects model meta-analyses to assess changes in the aforementioned outcomes.

RESULTS

We identified 16 single-arm studies, 2 crossover and 3 parallel-arm nonrandomized controlled trials and 5 crossover and 5 parallel-arm randomized controlled trials. In an analysis of 23 study arms or cohorts (n = 2221), ultrapure dialysate resulted in a significant decrease in C-reactive protein (-3.2 mg/L; 95% CI -4.6, -1.8; P < 0.001). Other markers of inflammation and oxidative stress displayed similar significant improvements. Ultrapure dialysate also resulted in a significant increase in serum albumin (0.11 g/dL; 95% CI 0.02, 0.19; P = 0.011) and hemoglobin (0.40 g/dL; 95% CI 0.06, 0.75; P = 0.022), and a decrease in the weekly erythropoietin dose (-273 units; 95% CI -420, -126; P < 0.001). The results remained significant in analyses restricted to controlled trials.

CONCLUSIONS

Use of ultrapure dialysate in hemodialysis patients results in a decrease in markers of inflammation and oxidative stress, an increase in serum albumin and hemoglobin and a decrease in erythropoietin requirement. Although improvement in these surrogate endpoints might confer a cardiovascular benefit, a large trial with hard clinical endpoints is required.

High-flux versus low-flux membranes for end-stage kidney disease

BACKGROUND

Clinical practice guidelines regarding the use of high-flux haemodialysis membranes vary widely.

OBJECTIVES

We aimed to analyse the current evidence reported for the benefits and harms of high-flux and low-flux haemodialysis.

SEARCH METHODS

We searched Cochrane Renal Group's specialised register (July 2012), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1948 to March 2011), and EMBASE (1947 to March 2011) without language restriction.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared high-flux haemodialysis with low-flux haemodialysis in people with end-stage kidney disease (ESKD) who required long-term haemodialysis.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two authors for study characteristics (participants and interventions), risks of bias, and outcomes (all-cause mortality and cause-specific mortality, hospitalisation, health-related quality of life, carpal tunnel syndrome, dialysis-related arthropathy, kidney function, and symptoms) among people on haemodialysis. Treatment effects were expressed as a risk ratio (RR) or mean difference (MD), with 95% confidence intervals (CI) using the random-effects model.

MAIN RESULTS

We included 33 studies that involved 3820 participants with ESKD. High-flux membranes reduced cardiovascular mortality (5 studies, 2612 participants: RR 0.83, 95% CI 0.70 to 0.99) but not all-cause mortality (10 studies, 2915 participants: RR 0.95, 95% CI 0.87 to 1.04) or infection-related mortality (3 studies, 2547 participants: RR 0.91, 95% CI 0.71 to 1.14). In absolute terms, high-flux membranes may prevent three cardiovascular deaths in 100 people treated with haemodialysis for two years. While high-flux membranes reduced predialysis beta-2 microglobulin levels (MD -12.17 mg/L, 95% CI -15.83 to -8.51 mg/L), insufficient data were available to reliably estimate the effects of membrane flux on hospitalisation, carpal tunnel syndrome, or amyloid-related arthropathy. Evidence for effects of high-flux membranes was limited by selective reporting in a few studies. Insufficient numbers of studies limited our ability to conduct subgroup analyses for membrane type, biocompatibility, or reuse. In general, the risk of bias was either high or unclear in the majority of studies.

AUTHORS' CONCLUSIONS

High-flux haemodialysis may reduce cardiovascular mortality in people requiring haemodialysis by about 15%. A large well-designed RCT is now required to confirm this finding.

Influence of dialysis modality and membrane flux on quality of life in hemodialysis patients

BACKGROUND

The quality of life in patients undergoing hemodialysis is significantly disturbed. There are data that hemodiafiltration (HDF) may be more effective than conventional hemodialysis in the removal of uremic toxins and may reduce frequency and severity of intradialytic and postdialysis adverse symptoms in patients. Also, some researchers suggest advantages of using high-flux membranes compared with low-flux.

OBJECTIVE

The aim of this study was to examine whether hemodialysis modality and membrane flux, independent of membrane biocompatibility, make differences in quality of life in patients.

METHODS

In our cross-sectional study, we evaluated 124 patients who were divided, based on therapy, into three groups: online HDF, high-flux hemodialysis, and low-flux hemodialysis. Data were collected using the Short Form-36 questionnaire combined with special questionnaire, which included demographic and clinically related questions.

RESULTS

Health-related quality of life was better in patients on HDF compared with patients on hemodialysis, especially compared with low-flux hemodialysis patients in most of the scales and in both dimensions: physical component scale and mental component scale. There were no statistically significant differences in Short Form-36 domains between high-flux hemodialysis and low-flux hemodialysis.

CONCLUSION

Our data suggest the potential advantages of HDF with regard to influence on quality of life, which is sufficient to justify further research in prospective and longitudinal study design.

Do clinical outcomes in chronic hemodialysis depend on the choice of a dialyzer?

Nephrologists are presented with a range of choices when selecting a dialyzer for chronic hemodialysis. Dialyzers differ in the material, structure, permeability and surface area of their membrane, and how the dialyzer is sterilized. Opinions vary regarding the impact of dialyzer characteristics on patient outcomes and which, if any, of these properties to take into account when choosing a dialyzer can be confusing. In the general dialysis population, there is no compelling evidence that the choice of a membrane material from among those materials currently in clinical use has a significant impact on morbidity or mortality (although there are rare patients who will react adversely to a given dialysis membrane). Similarly, most dialyzers are capable of adequately removing small solutes, such as urea, provided they are used with an appropriate blood flow rate and treatment time to ensure delivery of a single-pool Kt/V(urea) of at least 1.25 for men and 1.65 for women. However, in some dialysis patient subpopulations, the results of randomized clinical trials suggest that use of dialyzer containing high-flux membranes confers an outcome advantage. The extent to which this advantage is realized might also depend on how the dialyzer is used, with application in convective therapies such as hemodiafiltration being superior to diffusive therapies such as hemodialysis. This possibility is currently the subject of several large clinical trials.

High-flux dialyzers, backfiltration, and dialysis fluid quality

Currently, high-flux hemodialysis is the most common mode of dialysis therapy worldwide. Its steadily increasing use is largely based on the desire to reduce the excessively high morbidity and mortality of end-stage renal disease patients maintained on conventional dialysis (low-flux, mostly cellulosic membranes) by offering better biocompatibility and enhanced removal of uremic toxins. Two large randomized trials suggest a survival benefit for selected subgroups of high-flux dialysis patients such as diabetics, patients with hypoalbuminemia, or patients who have been on dialysis for a long period (>3.7 years). The major disadvantage of high-flux hemodialysis relates to the use of dialysis fluid, which is commonly not pure and may endanger patients treated with high-flux hemodialysis. Endotoxin fragments and other bacterial substances derived from bacteriologically contaminated dialysis fluid may, even at bacterial counts or endotoxin concentrations within the limits of accepted standards of dialysis fluid purity, enter from the dialysate into the patient's blood either by convective transfer (backfiltration) or by movement down the concentration gradient (backdiffusion). Repeated exposure of high-flux hemodialysis patients to backtransport of dialysate contaminants aggravates the uremia-associated inflammatory response syndrome and contributes to long-term morbidity. At present, the only solution to circumvent the risks of backtransport is the use of dry powder cartridges for bicarbonate concentrate and the use of bacteria- and endotoxin-retentive filters for the online production of ultrapure dialysis fluid. Use of ultrapure dialysis fluid (bacteria <0.1 CFU/ml and endotoxin <0.03 IU/ml) has been found to reduce inflammation and comorbidities in clinical investigations compared to commercial dialysis fluid. The European Renal Association and a number of national societies in Europe or in Japan strongly recommend the use of ultrapure dialysis for high-flux hemodialysis.

Rheumatic complications of long term treatment with hemodialysis

Patients undergoing hemodialysis therapy develop serious osteoarticular diseases. The treatment is based on prevention. The aim of our study is to determine the frequency and the associated factors to the rheumatic manifestations in hemodialysis patients. A cross-sectional study was conducted, including all hemodialysed patients in our dialysis unit. Information was obtained from patients' symptoms, examination findings, and biological and radiological signs. The frequency of symptoms was 70% in our patients. It was proportional to the duration of hemodialysis and number of hemodialysis sessions per week. Early transplantation is of course a plausible solution, but other therapies such as improved dialysis must be considered.

Benefits of first-half intensive haemodiafiltration for the removal of uraemic solutes

AIM

Haemodiafiltration (HDF) is the most efficient blood purification method and can remove a wide spectrum of solutes of different molecular weights (MW). The purpose of this study was to investigate whether the removed amounts of solutes, especially the larger molecules, could be increased by changing the HDF filtration procedure.

METHODS

A new first-half intensive HDF treatment (F-HDF) was designed, whereby convective clearance is intensively forced during the first half of a HDF session. We compared the removed amounts of solutes in the same group of nine patients treated by F-HDF, constant rate-replacing HDF (C-HDF) and a high-flux haemodialysis (HD).

RESULTS

F-HDF can remove significantly larger amounts of α(1) -microglobulin (MG), molecular weight (MW) 33,000, compared with HD and C-HDF (30.1 ± 15.1 vs 12.4 ± 0.3, 15.0 ± 3.1 mg, P < 0.01). Regarding the removal amounts and clear space of β(2) MG, MW 11,800, there were no significant differences between the three treatment modalities. Regarding amounts of creatinine, urea nitrogen and phosphorus, there were no significant differences between the three treatment modalities.

CONCLUSION

In post-replacement HDF with a high-flux membrane dialyzer, the method used in the present study in which replacement is completed during the first half of the process, is associated with a greater rate of larger molecule removal than the conventional uniform replacement method.

Subcutaneous beta2-microglobulin amyloid shoulder nodulesin a long-term hemodialysis patient

beta2-Microglobulin accumulation with resultant tumor formation is a known albeit rare complication of long-term hemodialysis. Although these tumors may occur in various locations, subcutaneous shoulder nodules are very infrequent. We report a patient with end-stage kidney failure who had been on hemodialysis for 16 years and noted left shoulder nodules after initiation of hemodialysis; these nodules had slowly grown larger. Biopsy of one of these nodules revealed beta2-microglobulin amyloidosis by histopathology, Congo red stain, electron microscopy, and immunohistochemistry.

High-quality dialysis: a lesson from the Japanese experience: Effects of membrane material on nutritional status and dialysis-related symptoms

High-quality dialysis does not always mean high efficiency; dialysis should maintain nutritional balance and full biocompatibility. In undergoing treatment with polymethylmethacrylate (PMMA) and/or ethylene vinyl alcohol copolymer (EVAL) membrane dialysers, the body weight decrease caused by polysulfone membrane has been dramatically improved for those receiving predilution online haemodiafiltration (HDF) as well. These membranes are assumed to somewhat suppress the clearance of small molecular weight substances to maintain an exquisite balance of broadly removing low molecular weight proteins. This removal process is assumed to be extremely close to the balance maintained by the clearing characteristics of the kidneys. On the other hand, fluid purification is also one of the important factors in high-quality dialysis. Bacteriological contamination of dialysis fluid is one of the serious factors that deteriorate the biocompatibility of dialysis therapy.

From this therapeutic concept, the patient survival rate is excellent in our facilities: the 1-year survival rate is 91.1% and the 5-year survival rate is 76.6%, although the mean age of our patients is 69 years. We usually adjust the therapeutic modality based on patient complaints, and we call this concept ‘patient-oriented dialysis’ (POD). In the POD system, the prevalence of uraemic pruritus or sleep disturbances was lower than that of the DOPPS. The protein-leaking dialysis modalities with PMMA, EVAL or predilution online HDF form the key concept in the POD system.

Effect of different synthetic membranes on laboratory parameters and survival in chronic haemodialysis patients

Background. A number of studies suggested that the type of dialysis membrane is associated with differences in long-term outcome of patients undergoing haemodialysis, both in terms of morbidity and mortality. In the majority of dialysis units, synthetic membranes are being used. However, no studies are available so far for comparison between different biocompatible membranes. Therefore, we studied the influence of high- and low-flux polysulphone membranes (PS) in comparison with polymethylmethacrylate (PMMA) membranes on mortality and morbidity on the basis of various laboratory parameters. Methods. In a cohort study, data of 260 consecutive haemodialysis patients entering our dialysis unit in the years 2003-07 were collected, comparing 435 PS patient-years and 85 PMMA patient-years. PMMA membranes (n = 33) were used for those patients who did not tolerate (e.g. for pruritus) PS membranes (n = 227). Low-flux dialysers (n = 233) were compared with high-flux (n = 37). Laboratory values were evaluated by unpaired t-test, and mortality was evaluated by log-rank test and Cox regression analysis adjusted for age, diabetes and laboratory parameters. Results. Patients in our dialysis unit had a high cardiovascular risk as demonstrated by a proportion of 63% of peripheral arterial disease. Despite this, cumulative survival was almost 60% after 5 years on dialysis. It was slightly but not significantly higher in patients on PMMA (68%) compared with PS dialysers (54%) and on high-flux (61%) versus low-flux membranes (54%). After accounting for the confounding effect of age and diabetes in the multivariate Cox regression analysis, there was no impact of the membranes used (high- or low-flux, PMMA or PS) on survival. Only age at the onset of dialysis showed a significant influence on survival (P ≤ 0.001). Independent predictors of mortality in all patients in the multivariate Cox regression analysis were age, haemoglobin, leucocytes, C-reactive protein (CRP) and creatinine. Laboratory parameters between the high- and low- flux groups were not different. PS-treated patients showed significantly (P ≤ 0.05) higher values for leucocytes, thrombocytes, ferritin, and CRP and lower values for haemoglobin, transferrin, creatinine, uric acid, creatine kinase (CK), and sodium than PMMA-treated patients. Irrespective of the membrane used, in deceased patients, the following laboratory values were higher than for patients alive: leucocytes, thrombocytes, ferritin and CRP; the following were lower: haemoglobin, iron, total protein, urea, creatinine, uric acid and CK. Conclusions. The data of 260 severely ill haemodialysis patients showed a slightly, but not significantly, reduced mortality in patients treated with PMMA membranes in comparison with PS and with high-flux membranes compared with low-flux. High- or low-flux membranes exhibited no difference in laboratory values. However, in PMMA patients, laboratory data with respect to inflammation, anaemia and nutrition were significantly improved compared with the PS group. A similarly positive laboratory pattern was seen in patients alive compared with patients deceased with both membrane types. The favourable effect of PMMA membranes may be explained by the reduced activation of catabolic components and inflammation, which, in turn, would result in an improved nutrition and better response to recombinant human erythropoietin.

Back to the future: middle molecules, high flux membranes, and optimal dialysis

Middle molecules can be defined as compounds with a molecular weight (MW) above 500 Da. An even broader definition includes those molecules that do not cross the membranes of standard low-flux dialyzers, not only because of molecular weight, but also because of protein binding and/or multicompartmental behavior. Recently, several of these middle molecules have been linked to the increased tendency of uremic patients to develop inflammation, malnutrition, and atheromatosis. Other toxic actions can also be attributed to the middle molecules. In the present publication we will consider whether improved removal of middle molecules by large pore membranes has an impact on clinical conditions related to the uremic syndrome. The clinical benefits of large pore membranes are reduction of uremia-related amyloidosis; maintenance of residual renal function; and reduction of inflammation, malnutrition, anemia, dyslipidemia, and mortality. It is concluded that middle molecules play a role in uremic toxicity and especially in the processes related to inflammation, atherogenesis, and malnutrition. Their removal seems to be related to a better outcome, although better biocompatibility of membranes might be a confounding factor.

Neuromuscular disease in the dialysis patient: an update for the nephrologist

Neuromuscular disease is an extremely common complication of end-stage kidney disease (ESKD), manifesting in almost all dialysis patients, and leading to weakness, reduced exercise capacity, and disability. Recent studies have suggested that hyperkalemia may underlie the development of neuropathy. As such, maintenance of serum K(+) within normal limits between periods of dialysis in ESKD patients manifesting early neuropathic symptoms may reduce neuropathy development and progression. For patients with more severe neuropathic syndromes, increased dialysis frequency or a switch to high-flux dialysis may prevent further deterioration, while ultimately, renal transplantation is required to improve and restore nerve function. Exercise training programs are beneficial for ESKD patients with muscle weakness due to neuropathy or myopathy, and are capable of improving exercise tolerance and quality of life. Specific treatments have recently been evaluated for symptoms of autonomic neuropathy, including sildenafil for impotence and midodrine for intra-dialytic hypotension, and have been shown to be effective and well tolerated. Other important management strategies for neuropathy include attention to foot care to prevent callus and ulceration, vitamin supplementation, and erythropoietin. Treatment with membrane-stabilizing agents, such as amitryptiline and gabapentin, are highly effective in patients with painful neuropathy.

Characteristics of dialysis-related amyloidosis in patients on haemodialysis therapy for more than 30 years

BACKGROUND

Dialysis-related amyloidosis is one of the chronic the complications of haemodialysis. We conducted an investigation of dialysis-associated amyloidosis in extremely long-term survivors.

METHODS

Twenty-one patients on haemodialysis for more than 30 years ('30+' group) and 13 patients on haemodialysis for 20-30 years ('20-30' group) at Sangenjaya Hospital were enrolled in this study. The frequencies of operations for conditions related to haemodialysis-related amyloidosis were examined.

RESULTS

The mean age at the start of haemodialysis was younger in the '30+' group (29.1 +/- 7.3 years) than in the '20-30' group (40.5 +/- 8.2 years, P = 0.0003). Eighteen (85.7%) patients had undergone surgery for CTS, six (28.6%) had undergone surgery for trigger finger and six (28.6%) had undergone surgery for cervical destructive spondyloarthropathy (DSA) at 30 years after the start of haemodialysis therapy. Patients who were over the age of 30 years at the start of dialysis therapy more frequently underwent CTS operations (100%) than those who were under 30 years of age at the start of dialysis (76.9%; P = 0.025) in the '30+' group at 30 years after the start of haemodialysis. The frequencies of operations for CTS did not differ significantly between the '20-30' group and the '30+' group.

CONCLUSIONS

Haemodialysis-associated amyloidosis was common in extremely long-term survivors. Even though the mean age at the start of haemodialysis was younger in the '30+' group than in the '20-30' group, the frequency of operations for CTS did not differ. This may be attributable to the recent advances in haemodialysis technologies.

Serum beta2-microglobulin level is a significant predictor of mortality in maintenance haemodialysis patients

BACKGROUND

Beta(2)-microglobulin (beta(2)-M) is recognized as a surrogate marker of middle-molecule uraemic toxins and is a key component in the genesis of dialysis-associated amyloidosis. Few studies have evaluated the association of beta(2)-M levels with clinical outcome in dialyzed patients.

METHODS

The prognostic implication of serum beta(2)-M levels for the survival of haemodialysis patients was examined in 490 prevalent haemodialysis patients (60.1 +/- 11.8 years, haemodialysis duration of 87.4 +/- 75.7 months, 288 males and 202 females; 24% diabetics). The patients were divided into two groups according to their serum beta(2)-M levels: lower beta(2)-M group (n = 245) with serum beta(2)-M <32.2 mg/L (the median serum beta(2)-M) and higher beta(2)-M group (n = 245) with that >or=32.2 mg/L.

RESULTS

During the follow-up period of 40 +/- 15 months, there were 91 all-cause deaths, and out of them, 36 were from cardiovascular diseases. Kaplan-Meier analysis revealed that all-cause mortality in the higher beta(2)-M group was significantly higher compared to that in the lower beta(2)-M group (P < 0.001). Multivariate Cox proportional hazards analyses showed that serum beta(2)-M level was a significant predictor for all-cause mortality (hazard ratio, 1.05; 95% CI, 1.01-1.08; P = 0.005), and for non-cardiovascular mortality (hazard ratio, 1.06; 95% CI, 1.02-1.10; P = 0.006), after adjustment for age, gender, haemodialysis duration, the presence of diabetes, serum albumin and serum C-reactive protein.

CONCLUSION

These results demonstrate that the serum beta(2)-M level is a significant predictor of mortality in haemodialysis patients, independent of haemodialysis duration, diabetes, malnutrition and chronic inflammation, suggesting the clinical importance of lowering serum beta(2)-M in these patients.

Carpal tunnel syndrome and plasma beta2-microglobulin concentration in hemodialysis patients

As of the end of June 2005, 27 of 96 dialysis outpatients at our clinic had developed carpal tunnel syndrome (CTS). Of 19 patients who had undergone dialysis for 30 years or longer, 15 had CTS, whereas none of the 38 patients who had received dialysis for less than 10 years had CTS. These data reflect trends in CTS development: from 1983 the incidence of CTS increased for many years, but more recently there has been a decline in new cases of CTS. Comparison of the 27 CTS and 69 non-CTS dialysis patients at our clinic showed that those in the CTS group were older and had a longer duration of dialysis. Patients in the CTS group were found to have had a high plasma beta2-microglobulin (BMG) level in the distant past (15-21 years ago), but conversely had a much lower BMG level in recent years. Simple correlation analysis and multiple logistic regression analysis showed that the presence of CTS was correlated with high BMG levels in the distant past, in addition to age and duration of dialysis. These findings suggest that reduction of the plasma BMG level due to advances in dialysis therapy in recent years has contributed to the decreased incidence of CTS.